The present invention relates to a remote-operated integrated microactuator. In particular, an integrated microactuator according to the present invention may be advantageously, but not exclusively, used to actuate read/write transducers of hard disks.
As is known, hard disk actuating devices having a dual actuation stage recently have been proposed for fine control of a position of a read/write head with respect to a hard disk to be read or written. FIGS. 1 and 2 schematically show an example of a known hard disk actuating device 1 with a dual actuation stage. Shown in detail in FIG. 1, the hard disk actuation device 1 comprises a motor 2 (also called xe2x80x9cvoice coil motorxe2x80x9d)to which at least one suspension 5 formed by a lamina is fixed in projecting manner. At its free end, the suspension 5 has an R/W (read/write) transducer 6 (see FIG. 2) (also called a xe2x80x9csliderxe2x80x9d)disposed when in an operative condition to face a surface of a hard disk 7 (see FIG. 1). The R/W transducer 6 is rigidly connected to a coupling (called a xe2x80x9cgimbalxe2x80x9d 8), via a microactuator 9 interposed between the gimbal 8 and the R/W transducer 6. On one of its lateral surfaces, the RIW transducer 6, formed by a ceramic material body (e.g., AITiC), further has a read/write head 10 (which is magneto/resistive and inductive) that forms the read/write device proper.
In the actuating device 1, a first actuation stage is formed by the motor 2 that moves a unit including the suspension 5 and the R/W transducer 6 across the hard disk 7 during track seeking. A second actuation stage is formed by the microactuator 9 that finely controls the position of the R/W transducer 6 during tracking.
An embodiment of a microactuator 9 of a rotary electrostatic type is shown in diagrammatic form in FIG. 3, with the microactuator 9 shown only in part, given its axial symmetry. The microactuator 9 comprises a stator 17, which is integral with a die accommodating the microactuator 9 and bonded to the gimbal 8, and a rotor 11, intended to be bonded to the R/W transducer 6 and capacitively coupled to the stator 17.
The rotor 11 comprises a suspended mass 12 of substantially circular shape and a plurality of movable arms 13 extending radially towards the outside from the suspended mass 12. Each movable arm 13 has a plurality of movable electrodes 14 extending in a substantially circumferential direction and spaced at a same distance from each other. The rotor 11 further comprises anchoring and elastic suspension elements (shown as springs 15 in FIG. 3) for supporting and biasing of the rotor 11 through fixed regions 16.
The stator 17 comprises a plurality of fixed arms 18a, 18b extending radially inward and each bearing a plurality of fixed electrodes 19. In particular, associated with each movable arm 13 is a pair of fixed arms formed by a fixed arm 18a and a fixed arm 18b. Fixed electrodes 19 of each pair of fixed arms 18a, 18b extend towards an associated movable arm 13 and are intercalated or interleaved with the movable electrodes 14. The fixed arms 18a are all disposed on a same side of the respective movable arms 13 (on the right side in the example shown in FIG. 3) and are all polarized at a same potential via biasing regions 20a. Similarly the fixed arms 18b are all disposed on the other side of the respective movable arms 13 (on the left side in the example shown in FIG. 3) and are all biased at a same potential through biasing regions 20b. The fixed arms 18a and 18b are biased at different potentials to generate two different potential differences with respect to the movable arms 13 and cause the rotor 11 to rotate in one direction or the other. The known arrangement shown in FIG. 2 does, however, have several disadvantages. The microactuator 9 is subject to intense mechanical stresses due to impacts of the RIW transducer 6 against the hard disk 7 that may damage the microactuator 9. Furthermore, the microactuator 9 is exposed to an external environment, and therefore is not protected from extraneous particles present in the environment that may compromise its satisfactory operation. Also, biasing voltages supplied to the microactuator 9 to obtain desired movements of the R/W transducer 6 have relatively high values (of the order of 80 V) which may cause electrostatic interference in the direction of the R/W transducer 6.
An advantage of the present invention is to provide an integrated microactuator which overcomes the disadvantages of the proposed microactuators described above.
Embodiments of the invention provide an integrated microactuator comprising a motor element, the motor element including a stator element and a rotor element coupled reciprocally thereto. The integrated microactuator further comprises a separate actuator element and a transmission structure interposed between the motor element and the actuator element to transmit a movement of the motor element into a corresponding movement of the actuator element.